Moldagem de briquetes com finos de carvão vegetal aglutinados com parafina: caracterização de algumas propriedades.

Abstract

The aim of this study was to evaluate the properties of briquettes made from charcoal fines bonded with paraffin. To prepare them were used three fractions of fine coal (20, 35 and 60 mesh) and a binder, the paraffin. Initially, the coal was fragmented into small pieces, milled and sieved and the fines thus produced were mixed and homogenized to the binder in a proportion of 15, 25 and 35%. The mixtures were taken to the oven, so the paraffin is melted and then taken to a laboratory hydraulic pressure where was applied a compression force of 1250 Kgf.cm-2 for 30 seconds. According to the results, the briquettes produced had an increase in heating power in accordance with increase in the content of binder reaching 8588 kcal.Kg-1 in briquettes bound with 35% of paraffin. The ash content was not affected by the binder since the paraffin produces no ash in the process of combustion. It was also accomplished the combustion index test using a combustion device, where temperature vs. time graphs and mass vs. time graphs were generated in order to learn more of its properties in the combustion process. The mechanical strength was indeed an important feature provided by the binder paraffin to the briquettes reaching a diametrical compression strength of 0.785 MPa, significant value compared to the lack of resistance in the briquettes without the binder, and generating fine in percentage of 5.38%, showing high mechanical strength, essential property in the process of transportation and storage. The assay distribution in paraffin briquette showed that the binder migrated to the edges, characterizing it as a binder type film. The higher the content of paraffin binder, the lower the moisture content of the briquettes. The moisture absorption was minimal with average values of 5%, presenting the moisture protection provided by the binder